Any idea if this is 6mm2 or 10mm2 cable?

[katheh]

Looking to upgrade shower from broken 7.5kW. Trying to work out whether I have 6mm2 or 10mm2 cable in the current installation (it's connected to a 40A MCB). Can anyone tell from these pictures? Copper strands seems to be just over 1mm diameter and brown cable is about 6mm diameter.

 

[terryplumb]

If the earth conductors are rigid copper,not stranded ,the cable is not 10 mm²

 

[katheh]

Thanks @terryplumb . Earth cable looks like this so I guess it is indeed 10mm2.

 

[333rocky333]

...

 

[terryplumb]

It would appear so ,but examine the outer grey sheath ,the cable size should be embossed into it.

 

[katheh]

It would appear so ,but examine the outer grey sheath ,the cable size should be embossed into it.

I can't get to that very easily unfortunately

 

[terryplumb]

What KW rated shower are you thinking of installing ?

 

[JohnW2]

I can't get to that very easily unfortunately

I agree that it almost certainly is 10mm², but if you wanted to be absolutely certain (without being able to see/read the sheath) and had a micrometer or vernier caliper, you could count the cores and measure the diameter of one of them - and then calculate to total cross-sectional area.

Do I take it that you cannot see (hence read) the sheath at either end of the cable, and/or are you not comfortable looking inside the CU?

Kind Regards, John

 

[katheh]

What KW rated shower are you thinking of installing ?

10.8kW ideally or the highest possible without the disruption of changing the cable (current shower is 7.5kW). I believe the MCB will need to be changed to 50A. I'll get an electrician in to do it but helpful to know in advance what I currently have. Plumber assumed cable would be 6mm2 without even looking and told me to get that upgraded to 10mm2 first.

 

[katheh]

I agree that it almost certainly is 10mm², but if you wanted to be absolutely certain (without being able to see/read the sheath) and had a micrometer or vernier caliper, you could count the cores and measure the diameter of one of them - and then calculate to total cross-sectional area.

Do I take it that you cannot see (hence read) the sheath at either end of the cable, and/or are you not comfortable looking inside the CU?

Kind Regards, John

Yeah, just been searching the house for a micrometer or vernier caliper and have concluded I don't have one! Cable goes straight into the ceiling by the shower and is boxed in above the CU. I could get in the crawl space in the eaves above the CU assuming all the cables go up there but might be tough to work out which is which. How would I look inside the CU?

 

[JohnW2]

10.8kW ideally or the highest possible without the disruption of changing the cable (current shower is 7.5kW). I believe the MCB will need to be changed to 50A.

As has been said, it almost certainly is 10mm² cable.

However, even if it were 6mm², if installed with 'Method C', that would have a current-carrying-capacity of 47A. A "10.8 kW" shower almost certainly means 10.8 kW at 240V, which corresponds to just over 43A at 230V. Hence, if it were 'Method C', then it would seem that 6mm² cable on a 45A MCB would be adequate.

Kind Regards, John